Power capacitor and method of manufacturing the same

Abstract

Disclosed is a power capacitor having a fireproof function, and a method of manufacturing the same. The power capacitor includes an internal capacitor unit including a capacitor case (1), an element assembly (2) disposed in the capacitor case (1), an insulating fluid (3) filled in the capacitor case (1), a pair of bushings (4), and a pair of capacitor electrodes (5). The power capacitor further includes an outer case (7) in which the internal capacitor unit is disposed, and a non-flammable solid mineral material (8) filled between the outer case (7) and the capacitor case (1). The pair of bushings (4) is configured to be airtightly fixed to and extend through the capacitor case (1) and the outer case (7), and the pair of capacitor electrodes (5) is configured to extend through the capacitor case (1) and the outer case (7) via the pair of bushings (4).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a power capacitor having a fireproof function, and a method of manufacturing the same. BACKGROUND

[0002] Power capacitors are widely used in underground / indoor substations, and mining industries and other applications having high-level fireproof requirements.

[0003] Currently, a typical high-voltage power capacitor includes a metal capacitor case and a plurality of capacitor elements electrically connected in parallel and in series. Each of the capacitor elements includes a plurality of very thin electrode layers made of aluminum foil and separated by a film of dielectric material. The film of dielectric material is usually in the form of a polymer film, such as a polypropylene film, and is wound into a roll, which is flattened to be able to be stacked into an element assembly. The assembly is disposed within the capacitor case filled with an insulating fluid.

[0004] Since the insulating fluid is a flammable material, a fire accident can occur once the insulating fluid is leaked due to a rupture of the case. At the same time, the filling material of a dry-type capacitor cannot satisfy high-level (e.g., UL94 V-0) fireproof requirements. Therefore, there is a strong demand for a reliable fireproof power capacitor in the market. SUMMARY

[0005] In view of the above, the present disclosure aims to provide a power capacitor having a fireproof function, which overcomes the drawbacks of the prior art.

[0006] To this end, a first aspect of the present disclosure provides a power capacitor including an internal capacitor unit including a capacitor case, an element assembly disposed in the capacitor case, an insulating fluid filled in the capacitor case, a pair of bushings, and a pair of capacitor electrodes. The power capacitor further includes an outer case in which the internal capacitor unit is disposed, and a non-flammable solid mineral material filled between the outer case and the capacitor case. The pair of bushings is configured to be airtightly fixed to and extend through the capacitor case and the outer case, and the pair of capacitor electrodes is configured to extend through the capacitor case and the outer case via the pair of bushings.

[0007] An effect obtainable based on this structure is that the possibility of leakage of the insulating fluid is significantly reduced by adding an additional outer case in combination with the non-flammable solid mineral material filled between the outer case and the capacitor case, thereby improving the fireproof performance of the power capacitor.

[0008] Further, since the optimized non-combustible solid mineral material has good thermal conductivity, in use, the additional outer shell and the non-combustible solid mineral material layer do not affect the heat dissipation of the power capacitor, thereby ensuring the thermal performance of the power capacitor.

[0009] In addition, the non-combustible solid mineral material has a noise reduction performance, thereby improving the acoustic performance of the power capacitor.

[0010] According to a preferred embodiment of the present disclosure, the non-combustible solid mineral material includes at least one of sand, vermiculite, slag, and perlite.

[0011] According to a preferred embodiment of the present disclosure, the non-combustible solid mineral material includes sand and perlite in a volume ratio of 4:1.

[0012] According to a preferred embodiment of the present disclosure, the non-combustible solid mineral material has a particle diameter of 1 mm to 3 mm.

[0013] According to a preferred embodiment of the present disclosure, the non-combustible solid mineral material is added with at least one of water, a solid-liquid phase change material, a fireproof fluid, and a fireproof powder.

[0014] According to a preferred embodiment of the present disclosure, the non-combustible solid mineral material has a moisture content of 0% to 60%.

[0015] According to a preferred embodiment of the present disclosure, the non-combustible solid mineral material has a moisture content of 30%.

[0016] According to a preferred embodiment of the present disclosure, the outer shell includes a body having a top opening, and a top cover configured to be fixed to the body to cover the top opening, and the top cover is provided with a pair of holes through which the pair of bushings pass.

[0017] According to a preferred embodiment of the present disclosure, the internal capacitor unit further includes a sealing flange fitted on each of the bushings and airtightly fixed to the capacitor case.

[0018] According to a preferred embodiment of the present disclosure, the power capacitor further includes a sealing material filled between each of the bushings and the outer shell.

[0019] According to a preferred embodiment of the present disclosure, at least a portion of the capacitor case is configured in a wavy structure or a convex structure.

[0020] According to a preferred embodiment of the present disclosure, the power capacitor further includes a plurality of positioning members having the same thickness, which are arranged between the capacitor case and the outer shell to make the non-combustible solid mineral material uniform.

[0021] A second aspect of the present disclosure provides a method for manufacturing a power capacitor, the method comprising: providing an inner capacitor unit including a capacitor case, an element assembly arranged in the capacitor case, an insulating fluid filled in the capacitor case, a pair of bushings, and a pair of capacitor electrodes; providing an outer case and arranging the inner capacitor unit in the outer case; and providing a non-flammable solid mineral material and filling the non-flammable solid mineral material between the outer case and the capacitor case. The pair of bushings is configured to be airtightly fixed to the capacitor case and the outer case and to extend through the capacitor case and the outer case, and the pair of capacitor electrodes is configured to extend through the capacitor case and the outer case via the pair of bushings.

[0022] According to a preferred embodiment of the present disclosure, the outer case includes: a body having a top opening; a top cover configured to be fixed on the body to cover the top opening, and the top cover is provided with a pair of holes through which the pair of bushings pass.

[0023] According to a preferred embodiment of the present disclosure, the method further comprises: providing a plurality of positioning members of equal thickness arranged between the capacitor case and the outer case to make the non-flammable solid mineral material uniform.

[0024] Since the non-flammable solid mineral material is inexpensive, non-toxic and environmentally friendly, the method for manufacturing the power capacitor is easy to implement.

[0025] In general, unless otherwise defined herein, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field. Unless explicitly stated otherwise, all references to "a / an / the element, apparatus, component, means, step, etc." are to be interpreted to mean at least one example of that element, apparatus, component, means, step, etc. BRIEF DESCRIPTION OF DRAWINGS

[0026] Other features and advantages of the present disclosure will be better understood through the following preferred embodiments, which are described in detail with reference to the accompanying drawings, in which like reference numerals indicate like or analogous parts.

[0027] Figure 1 is a schematic structural diagram of an embodiment of a power capacitor according to the present disclosure;

[0028] Figure 2 is Figure 1 is an enlarged view of a bushing of the power capacitor shown in FIG. 1; and

[0029] Figure 3 is a schematic diagram showing Figure 1 is a schematic diagram showing the relationship between the water content and the thermal conductivity of the non-flammable solid mineral material of the power capacitor shown in FIG. 1. DETAILED DESCRIPTION

[0030] The implementations and uses of the embodiments will be discussed in detail below. However, it should be understood that the specific embodiments discussed are merely for purposes of illustration and are not intended to limit the scope of protection of the present disclosure.

[0031] It should be noted that the accompanying drawings are used to illustrate and describe the present disclosure, and are also helpful to explain the present disclosure when necessary.

[0032] Figure 1 is a schematic structural view of an embodiment of the power capacitor according to the present disclosure. As shown in Figure 1 The power capacitor according to the present disclosure mainly includes an internal capacitor unit, a housing 7, and a non-flammable solid mineral material 8 filled between the housing 7 and the internal capacitor unit, as shown in

[0033] The internal capacitor unit has a configuration similar to that of the power capacitor in the prior art. Specifically, the internal capacitor unit mainly includes a capacitor case 1, an element assembly 2, an insulating fluid 3, a pair of bushings 4, and a pair of capacitor electrodes 5.

[0034] The capacitor case 1 is made of metal, for example, stainless steel, and generally has a cuboid shape. The capacitor case 1 is provided with an opening 11 for injecting the insulating fluid 3 into the capacitor case 1. The element assembly 2 is configured by stacking a plurality of capacitor elements that are electrically connected in parallel and in series, and forms a capacitor core arranged in the capacitor case 1. Each of the capacitor elements includes a plurality of very thin electrode layers made of aluminum foil and separated by a film of dielectric material, such as a polypropylene film, and the film of dielectric material is wound into a roll. The insulating fluid 3 filled in the capacitor case 1 can be insulating oil in which the element assembly 2 is immersed. As shown in Figure 1 The pair of bushings 4 are airtightly fixed to the top of the capacitor case 1 and extend through the top. The pair of capacitor electrodes 5 electrically connected with the element assembly 2 extend through the top of the capacitor case 1 via the pair of bushings 4.

[0035] Figure 2 is an enlarged view of one of the bushings 4 of the power capacitor shown in Figure 1 As shown in Figure 2 The internal capacitor unit can further include a sealing flange 6 that is sleeved on each of the bushings 4 and airtightly fixed to the capacitor case 1. Specifically, the pair of bushings 4 are made of an insulating material, such as ceramic, and the sealing flange 6 that is sleeved on each of the bushings 4 and generally made of metal is compressed and adhered to each of the bushings 4, and is welded to the top of the capacitor case 1 so as to cover the gap between the capacitor case 1 and the pair of bushings 4, thereby avoiding leakage of the insulating fluid 3 through the gap.

[0036] However, the insulating fluid 3 can leak out due to the rupture of the capacitor case 1 and cause a fire accident. Therefore, the essence of the present disclosure is to add an additional case 7, in which a non-flammable solid mineral material 8 is filled between the case 7 and the capacitor case 1, in order to improve the fireproof performance of the power capacitor.

[0037] The case 7 in which the internal capacitor unit is arranged is made of metal, such as stainless steel, and has a generally cuboid shape. The case 7 is configured to be connected to a container in which the power capacitor is accommodated by using a copper-braided wire to ensure reliable grounding. Specifically, in some embodiments, the case 7 includes a body 71 and a top cover 72. The body 71 has a top opening, and the top cover 72 is fixed to the body 71, for example, welded to the body 71, so as to cover the top opening. The top cover 72 is provided with a pair of holes through which the pair of bushings 4 passes. That is, the pair of bushings 4 of the internal capacitor unit are hermetically fixed to the case 7 and extend through the case 7 via the pair of holes, and the pair of capacitor electrodes 5 extend through the case 7 via the pair of bushings 4. In view of the sealing performance, the power capacitor preferably includes a sealing material, such as polyurethane foam, which is filled between each of the bushings 4 and the top cover 72 of the case 7 so as to cover the gap between the edges of the pair of holes and the pair of bushings 4, thereby avoiding leakage of the non-flammable solid mineral material 8 through the gap.

[0038] For example, the non-flammable solid mineral material 8 can include at least one of sand, vermiculite, slag, and perlite. Each of the sand, vermiculite, and slag has good thermal conductivity, the detailed comparison of which is shown in the following table. It should be noted that the "thickness" of the material refers to the distance between the case 7 and the capacitor case 1, and the "△t" of the material refers to the temperature rise of the material when the power capacitor is in use.

[0039]

[0040] Perlite is a mineral substance, and its thermal conductivity is lower than each of the sand, vermiculite, and slag. However, the weight of perlite is lower than each of the sand, vermiculite, and slag, so it can reduce the weight of the power capacitor. As a preferred example, the non-flammable solid mineral material 8 can be a mixture of sand and perlite, and the volume ratio of the sand and perlite is preferably 4:1.

[0041] Preferably, the particle diameter of the non-flammable solid mineral material 8 is 1 mm to 3 mm, which can improve the thermal conductivity and noise reduction performance of the power capacitor.

[0042] Preferably, the non-combustible solid mineral material 8 is added with water or a solid-liquid phase change material such as paraffin for improving the heat conduction performance of the power capacitor. The moisture content of the non-combustible solid mineral material 8 can be 0% to 60%. As a preferred example, the moisture content of the non-combustible solid mineral material 8 is 30%. In some embodiments, the non-combustible solid mineral material 8 is alternatively added with a fireproof fluid and / or a fireproof powder.

[0043] Figure 3 is a graph showing the relationship between the moisture content and the thermal conductivity of the non-combustible solid mineral material 8 of the power capacitor. As shown in Figure 3 the thermal conductivity of the non-combustible solid mineral material 8 will increase as its water content increases. However, considering that the non-combustible solid mineral material 8 has the function of absorbing / containing the leaked insulating fluid 3, the moisture content of the non-combustible solid mineral material 8 is unlikely to be too high.

[0044] Preferably, at least a portion of the capacitor case 1 is configured in a wavy structure or a convex structure so as to increase the contact surface of the capacitor case 1 with the non-combustible solid mineral material 8, thereby further improving the heat conduction performance of the power capacitor.

[0045] The three-dimensional size of the outer case 7 is about 20 mm to 40 mm larger than that of the capacitor case 1. That is, the distance between the outer case 7 and the capacitor case 1, i.e., the thickness of the non-combustible solid mineral material 8, is about 10 mm to 20 mm. In order to facilitate the positioning of the capacitor case 1 in the outer case 7 and the uniform distribution of the non-combustible solid mineral material 8 between the capacitor case 1 and the outer case 7, in some embodiments, the power capacitor can further include a plurality of positioning members of equal thickness arranged between the capacitor case 1 and the outer case 7. It should be noted that the "thickness" direction of the positioning members corresponds to the thickness direction of the non-combustible solid mineral material 8. For example, in the case of a cuboid capacitor case 1 and a cuboid outer case 7, five positioning members of equal thickness can be respectively provided on the four lateral outer surfaces and the bottom outer surface of the capacitor case 1 or on the five corresponding inner surfaces of the outer case 7, and the five positioning members have equal thickness so as to uniformly distribute the non-combustible solid mineral material 8 when the internal capacitor unit is placed into the outer case 7.

[0046] A method for manufacturing the above-described power capacitor is described below.

[0047] First, an internal capacitor unit including a capacitor case 1, an element assembly 2, an insulating fluid 3, a pair of bushings 4, and a pair of capacitor electrodes 5 is provided. It should be noted that the capacitor elements forming the element assembly 2 are electrically connected in parallel and in series according to the required capacitor voltage, capacity, and other parameters.

[0048] Then, the outer case 7, which preferably includes the body 71 and the top cover 72, is provided, and the internal capacitor unit is seated into the body 71 of the outer case 7. The above-mentioned positioning members of equal thickness can be arranged on the outer surface of the capacitor case 1, or on the inner surface of the body 71 of the outer case 7.

[0049] Then, the non-combustible solid mineral material 8 is provided and filled between the body 71 of the outer case 7 and the capacitor case 1. In the case where the non-combustible solid mineral material 8 is added with water, after mixing the non-combustible solid mineral material 8 with water, it is generally necessary to cover the resulting mixture with a polyethylene film and leave it for about 24 hours, so that the particles of the non-combustible solid mineral material 8 can be uniformly dispersed, and so that the mixture can be kept moist before use. Further, in the case where the positioning members of equal thickness are arranged, the non-combustible solid mineral material 8 can be filled to the bottom of the body 71 until reaching a positioning height equal to the thickness of the non-combustible solid mineral material 8 (about 10 to 20 mm) before the internal capacitor unit is seated into the body 71, and then the body 71 can be seated on a vibration platform, and the non-combustible solid mineral material 8 is continuously filled between the body 71 and the capacitor case 1.

[0050] Finally, after the non-combustible solid mineral material 8 is completely filled between the outer case 7 and the capacitor case 1, the top cover 72 is airtightly fixed on the body 71 and the pair of bushings 4. In particular, the top cover 72 can be welded on the top of the body 71 by means of a welding robot, and then, since the pair of bushings 4 protrude out of the outer case 7 through the holes provided in the top cover 72, a polyurethane foam nozzle can be seated at the gap between the edges of the pair of holes and the pair of bushings 4 for introducing polyurethane foam into the gap, and finally the introduced polyurethane foam is shaped and sealed by a polyurethane sealant.

[0051] The technical content and technical features of the present disclosure have been disclosed above. However, it is conceivable that those skilled in the art can make various changes and improvements to the above-mentioned disclosed concepts under the innovative idea of the present disclosure, but these changes and improvements all belong to the protection scope of the present disclosure. The description of the above-mentioned embodiments is exemplary rather than limiting, and the protection scope of the present disclosure is defined by the appended claims.

Claims

1. A power capacitor comprising: an internal capacitor unit comprising: a capacitor case (1), an element assembly (2) arranged in the capacitor case (1), an insulating fluid (3) filled in the capacitor case (1), a pair of bushings (4), a pair of capacitor electrodes (5); an outer case (7) in which the internal capacitor unit is arranged; and a non-combustible solid mineral material (8) filled between the outer case (7) and the capacitor case (1), wherein the pair of bushings (4) is configured to be airtightly fixed to the capacitor case (1) and the outer case (1) and to extend through the capacitor case (1) and the outer case (7), and the pair of capacitor electrodes (5) is configured to extend through the capacitor case (1) and the outer case (7) via the pair of bushings (4), wherein the power capacitor further comprises a plurality of equal-thickness positioning members arranged between the capacitor case (1) and the outer case (7) in a manner to be disposed on a plurality of lateral outer surfaces and a bottom outer surface of the capacitor case (1) or on a plurality of corresponding inner surfaces of the outer case (7) to homogenize the non-combustible solid mineral material (8).

2. The power capacitor of claim 1, wherein, The non-combustible solid mineral material (8) comprises at least one of sand, vermiculite, slag, and perlite.

3. The power capacitor of claim 2, wherein, The non-combustible solid mineral material (8) comprises sand and perlite in a volume ratio of 4:

1.

4. The power capacitor of claim 1, wherein, The non-combustible solid mineral material (8) has a particle diameter of 1 mm to 3 mm.

5. The power capacitor of claim 1, wherein, The non-combustible solid mineral material (8) is added with at least one of water, a solid-liquid phase change material, a fireproof fluid, and a fireproof powder.

6. The power capacitor of claim 5, wherein, The non-combustible solid mineral material (8) has a moisture content of 0% to 60%.

7. The power capacitor of claim 6, wherein, The non-combustible solid mineral material (8) has a moisture content of 30%.

8. The power capacitor of any one of claims 1 to 7, wherein, The outer case (7) comprises: a body (71) having a top opening; and a top cover (72) configured to be fixed on the body (71) to cover the top opening, and provided with a pair of holes through which the pair of bushings (4) passes.

9. The power capacitor of any one of claims 1 to 7, wherein, The internal capacitor unit further comprises a sealing flange (6) sleeved on each of the bushings (4) and airtightly fixed to the capacitor case (1).

10. The power capacitor of any one of claims 1 to 7, wherein, The power capacitor further comprises a sealing material filled between each of the bushings (4) and the outer case (7).

11. The power capacitor of any one of claims 1 to 7, wherein, At least a portion of the capacitor case (1) is configured as a wavy structure or a convex structure.

12. A method of manufacturing a power capacitor, the method comprising: providing an internal capacitor unit comprising: a capacitor case (1), an element assembly (2) arranged in the capacitor case (1), an insulating fluid (3) filled in the capacitor case (1), a pair of bushings (4), a pair of capacitor electrodes (5); providing an outer case (7) and arranging the internal capacitor unit in the outer case (7); and a non-combustible solid mineral material (8) is provided and filled between the outer case (7) and the capacitor case (1), wherein the pair of bushings (4) is configured to be airtightly fixed to and extend through the capacitor case (1) and the outer case (7), and the pair of capacitor electrodes (5) is configured to extend through the capacitor case (1) and the outer case (7) via the pair of bushings (4), wherein the method further comprises: providing a plurality of equal-thickness positioning members arranged between the capacitor case (1) and the outer case (7) in a manner to be disposed on a plurality of lateral outer surfaces and a bottom outer surface of the capacitor case (1) or on a plurality of corresponding inner surfaces of the outer case (7) to homogenize the non-combustible solid mineral material (8).

13. The method of claim 12, wherein, The outer case (7) includes: a body (71) having a top opening; and a top cover (72) configured to be fixed on the body (71) to cover the top opening, and provided with a pair of holes through which the pair of bushings (4) passes.

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